propane or diesel generator

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Donald

Donald

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More of my circling thinking about generators.

I am half convinced it only makes sense to buy a propane generator if you heat with propane and have an existing huge tank. Maybe 3/4 convinced.

I am looking at maybe $1500 to get propane tank or tanks totaling 250 gallons.

I could get a used decent diesel generator for $2000 and use it rather than the propane one I have been fixing up on and off (mostly off). I have 550 gallons of home heating oil capacity and usually have at least 300 gallons in the tanks.

Additionally we will move in roughly 4 years to a retirement friendly state. (NY is not retirement friendly, hear that Gov Cuomo). I have a top rate oil boiler. If it really broke for good I would get propane but would then need a 500 or 1000 gallon tank.
 
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Depending on what size generator that you are needing propane makes more sense for smaller ones. Fuel doesn't really go bad and saw online that someone calculated that 250 gallons of fuel would last 920 hours on a 500 watt continuous load. Getting tanks at the hardware store are cheap - Menards has 40 lb tanks for $78 and 100 lb tanks for $114. I would think those would last for a long time and you can get two tanks and keep one full all the time as a spare.

Bigger generators diesel makes more sense. Diesel kept dry doesn't degrade nearly as fast as gasoline and is more fuel efficient than propane or gas.
 
Originally Posted By: Donald

I am half convinced it only makes sense to buy a propane generator if you heat with propane and have an existing huge tank. Maybe 3/4 convinced.

I am looking at maybe $1500 to get propane tank or tanks totaling 250 gallons.


It's worked well for us for more than 20 years. Our underground propane tank is 1,500 gallons and serves the house, shop, grill and generator. We typically only use 500 or 600 gallons in a bad winter, so we always have a significant cushion should we have to use the generator for multiple days (which we have had to do in the past).
 
Propane- Pros
Fuel never goes bad
runs clean
no fuel pump to fail
works in the cold
fuel is relatively cheap

Cons
Doesn't always work when it's really cold
Regulators can stick (not often but it happens)
need a 200 gallon or bigger tank
can't run to the store for more fuel in an emergency

Diesel- Pros
Readily available fuel
Can run on kerosene in a pinch
can be plumbed into home heating oil system
no tank rental

Cons
Fairly expensive fuel
Fuel can go bad, grow algae or pick up water
stinky when running
requires a pump to lift fuel to the engine
won't always run in cold weather (has more to do with the fuel than the engine)
 
There is a huge BTU difference you have to account for.

Diesel: 139,000 BTU per gallon
Propane: 91,000

When comparing prices, price per BTU, not price per gallon.

Most of the newer propane gensets are all 3600 RPM and I don't think there are any good ones. Kohler makes one that uses a small 4 cyl (Suzuki? Ford?) that runs at 1800 RPM, but it isn't cheap.

Small Kubota Diesel engines that run at 1800 RPM will run for 20,000 hours.
 
The cheapest one you can find that can power essentials(e.g. Pull start portable). You mention moving in 4 years why spend $2000 and hassle of fuels etc for an events that odds are low of happening?

The generator adds little value add to a home more a nicety for next owner.
 
Originally Posted By: SVTCobra
Depending on what size generator that you are needing propane makes more sense for smaller ones. Fuel doesn't really go bad and saw online that someone calculated that 250 gallons of fuel would last 920 hours on a 500 watt continuous load. Getting tanks at the hardware store are cheap - Menards has 40 lb tanks for $78 and 100 lb tanks for $114. I would think those would last for a long time and you can get two tanks and keep one full all the time as a spare.

Bigger generators diesel makes more sense. Diesel kept dry doesn't degrade nearly as fast as gasoline and is more fuel efficient than propane or gas.


The issue is fuel vaporization. Even if I only planned on running my 8kw for an hour in the middle of winter with a decent load on it I would need a 250 gallon tank.

If you can carry a propane tank it will not be of much use in the winter to almost any size generator.

So its not about how long the tank will last, its how many BTUs per hour I can pull from the tank at 0F. I know its not a heater, but they list the requirements often in BTUs.
 
Originally Posted By: madRiver
The cheapest one you can find that can power essentials(e.g. Pull start portable). You mention moving in 4 years why spend $2000 and hassle of fuels etc for an events that odds are low of happening?

The generator adds little value add to a home more a nicety for next owner.


We loose power long enough and several times every year that I want to have a generator. I have several, but the one I am working on has an outdoor cabinet and would be mounted outside.

One power loss where the pipes for my boiler froze and broke would be tens of $1000s in cost.
 
I know things are not like here elsewhere (where everyone, urban or rural, has Natural Gas on the property) but Propane is the cleaner fuel and more consistent pricing year-round.

If your winter lows stay above about -35F Propane will be fine (below that and it Jells, which takes A LOT of heat to return to compressed gas because every BTU is evenly dispersed through every cubic foot of propane. When I lived in the sub-arctic, we would start wood fires under the tank, cover it with a tarp, and cover that with snow. If you do that, it only takes a day or two to heat up enough to flow).

Like everything, it makes sense to consolidate your non-electric fuel. So propane heat and a propane stove and clothes dryer makes sense if you install a propane generator. There is no real Diesel equivalent to those items, so in that case you are committing to an all-electric home. Things like that can sometimes make the decision easier to resolve.

If you absolutely need heat (boiler or hot water heating, or you are all-electric, or in a remote location, etc) then you should seriously consider a wood or pellet stove, or some similar backup that can run no matter what supply and environmental (temperature, storm) issues you might encounter. That might impact your home insurance, but the alternative could be disastrous.
 
After the Zombie Apocalypse the diesel may still run on clean burning liquefied zombie guts and you be hard pressed to find propane. :-)
 
I am also reminded that I might need to treat home heating oil with kerosene to run the diesel if it really got cold. Obviously I would try and buy normal treated diesel fuel so using home heating oil would be a last resort.
 
In places where people really need and can use generators for long times (months), like in the caribbean, diesel is the only way. They have propane but gensets are diesel.
 
The BTU post above is exactly right! But there is more to add.

A 250 gallon propane tank holds 200 gallons of actual fuel. 200 gallons of propane is also not fully usable, as the last few gallons won't evaporate rapidly enough to feed a generator at full load.

Because of a diesel engine's better efficiency, 90 gallons of diesel fuel will do the same work as 200 gallons of propane.

Also, in an emergency, a Diesel engine will run on just about any oily fuel. It's well within the possibility to run a generator on Olive Oil, Jet A, Kerosene, and much more.

A well designed diesel gen set is always the more efficient and more effective choice.
 
The diesels in generators nowadays are getting just as picky as anything else. You don't want to go using kerosene or heating oil Willy hilly. Even number 1 diesel isn't a good idea to run straight for very long. If you want to pay for #2 diesel for home heating it would be a no brainer to get a diesel generator.

You need to decide what size of generator you need before you decide on a fuel.
 
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Originally Posted By: jhellwig
The diesels in generators nowadays are getting just as picky as anything else. You don't want to go using kerosene or heating oil Willy hilly. Even number 1 diesel isn't a good idea to run straight for very long. If you want to pay for #2 diesel for home heating it would be a no brainer to get a diesel generator.

You need to decide what size of generator you need before you decide on a fuel.


8kw to 10kw. Water pump is largest consumer of power.
 
One of the propane companies that will rent tanks has too much hidden in the contract. Like the propane cost can go up, rental can go up, minimum usage charge, multi year contract and large pickup fee along with pump out fee (if tanks are picked up).
 
Originally Posted By: Cujet
The BTU post above is exactly right! But there is more to add.

A 250 gallon propane tank holds 200 gallons of actual fuel. 200 gallons of propane is also not fully usable, as the last few gallons won't evaporate rapidly enough to feed a generator at full load.

Because of a diesel engine's better efficiency, 90 gallons of diesel fuel will do the same work as 200 gallons of propane.

Also, in an emergency, a Diesel engine will run on just about any oily fuel. It's well within the possibility to run a generator on Olive Oil, Jet A, Kerosene, and much more.

A well designed diesel gen set is always the more efficients and more effective choice.


For a diesel to be efficient, you need a 1800 rpm engine. I am not getting a 100kw generator so that may not be a consideration. A 3600 propane vs diesel is what I need to look at.
 
Originally Posted By: Donald

For a diesel to be efficient, you need a 1800 rpm engine. I am not getting a 100kw generator so that may not be a consideration. A 3600 propane vs diesel is what I need to look at.


The little Kubota D905 you'll find in Terex/Amida light towers will run at 1800 RPM for 20,000 hours!! ...and burn VERY little fuel.

They are only 6.5Kw, though - and might not start a deep submersible well pump. But, they are on a built-in trailer!!
 
Originally Posted By: Donald


For a diesel to be efficient, you need a 1800 rpm engine. I am not getting a 100kw generator so that may not be a consideration. A 3600 propane vs diesel is what I need to look at.


That really is not so. Diesel BSFC is often best around 2200-2800 RPM depending on size (of course) and design. But BSFC does not increase to gasoline levels at 3600 RPM. Not to mention the abysmal consumption numbers of a highly loaded propane engine.

More interestingly, at high loads, high speed diesel engine BSFC does not increase much. For example a small high speed diesel has a best RPM efficiency of 2600RPM and BSFC of 0.43 lb/hr at full load, and climbs to 0.45 at 3600 RPM. An increase, yes, but only 9% percent. And a far cry from the 0.9 BSFC numbers of a common air cooled propane engine at full load.

In other words, a well designed small high speed diesel still consumes half the fuel of a propane engine.
 
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